Of the worst parties currently leading a democratic government, Zimbabwe's Zanu-PF obviously wins. I'd say after that it's probably close between Hungary's Fidesz, Venezuela's PSUV and Russia's United Russia (if Russia is a democracy, but they're at least comparable to Zimbabwe in that department). The next tier would be Mexico's PRI, Israel's Likud, Turkey's AKP, South Africa's ANC, Switzerland's SVP and Singapore's PAP.
The Muslim Brotherhood in Egypt probably fits in there somewhere, too, but it's hard to really place them as they haven't really done much governing, and democracy is so tenuous in Egypt at the moment that I'm not sure I'd call Egypt a democracy yet.
Disagree. Zanu-PF and Fidesz are obviously on the top of the table and United Russia one step below. However, I can't see why PSUV is worse than PRI, Likud, PAP or SVP. I'm not a follower of Chavez but too many people tend to depict the man as an evil wannabe dictator, and that's not the case. Putin or Ahmadineyad have a worse democratic record by far.
